Water meters to be mounted in the pipe conduits of a nominal diameter class and method for operating such water meters

ABSTRACT

The present invention relates to water meters for the installation in pipe lines of a nominal width-group and a method for operating such water meters, which operate according to the Woltmann principle. The present invention addresses the problem of avoiding the calibration expenditures for each of the nominal widths of the nominal width-group and the disadvantages entailed therein. The solution of this problem, stated generally, lies therein that in the water meters at the relevant site, namely in the annular channel ( 16 ) directly in front of the impeller wheel ( 8 ), independently of the nominal width of the connected pipe line, a substantially rectangular velocity distribution ( 19 ) obtains with stream lines directed substantially parallel to the wall of the annular channel ( 16 ), with these flow conditions being substantially identical at identical throughflows.

[0001] The present invention relates to a water meter according to the preamble of claim 1 as well as a method for operating water meters according to the preamble of claim 8.

[0002] Such water meters, which operate according to the Woltmann principle, are disclosed for example in WO 91/04462, DE 841 952, DE 37 32 703 A1, U.S. Pat. No. 3,811,323 and U.S. Pat. No. 3,999,432. They are installed in pipe lines of differing nominal widths, and in order not to have to manufacture for each nominal width a measuring insert adapted in terms of structural size, nominal widths are combined into groups of nominal widths, in which like measuring inserts, i.e. measuring inserts identical in structural size and of identical construction, are employed. Thereby the production costs for the measuring inserts can be lowered.

[0003] According to prior art, the measuring inserts of one nominal width-group must be calibrated for each rated value. This entails various disadvantages. For one, the expenditures during calibrating are thereby increased since equipment parts adapted to the different nominal widths must be made available. For another, servicing is difficult since the operators of the meters frequently state incorrect nominal widths in the event of a service request. The service technician in this case either brings to the site of installation an incorrect measuring insert, i.e. one calibrated to another nominal width or, preventively, carries along several measuring inserts calibrated to various nominal widths of the nominal width-group. A further disadvantage can be seen therein that the expenditure in warehousing increases since for each group of nominal widths a number corresponding to the number of the nominal widths combined therein, of calibrated measuring inserts must be kept in readiness.

[0004] The present invention addresses the problem of eliminating the above listed disadvantages of prior art.

[0005] This problem is solved according to the invention with water meters with the characteristics of claim 1 and with a method with the characteristics of claim 8.

[0006] Stated in general terms, the solution of this problem lies therein that in the water meters at the relevant site, namely in the annular channel directly in front of the impeller wheel, independently of the nominal width of the connected pipe line, a substantially rectangular velocity distribution obtains with stream lines substantially aligned parallel to the wall of the annular channel, wherein these flow conditions at identical throughflows are substantially identical. It is therefore only required to calibrate the measuring insert for one nominal width of the nominal width-group, but which subsequently without changing the adjustment and without repeated calibration can be employed in each nominal width of the nominal width-group.

[0007] In an advantageous implementation of the water meters the upstream holding means comprises a substantially perpendicular face of stream incidence, which transitions into a cylindrical or slightly conical diverging shell surface, which forms the inner wall of the annular channel, with the transition being shaped such that directly in front of the impeller wheel a substantially rectangular velocity distribution obtains.

[0008] This formation contributes to the fact that even in the case of the smallest or the smaller nominal widths of the nominal width-group not only identical integrated flow velocities are present in front of the impeller wheel but also that here uniform flow conditions obtain from which, viewed over the cross section of the annular channel, results a uniform flow against the vanes of the impeller wheel.

[0009] Further advantageous implementations of the water meters are evident in the remaining dependent claims.

[0010] In the following the invention will be explained in further detail in conjunction with an embodiment example and an associated drawing. It relates to water meters for the installation in pipe lines of the group of nominal widths from 50 to 100 mm. Part of this nominal width-group are the nominal widths conventionally and commonly used in practice of 50, 80 and 100 mm as well as, if appropriate, an additional fourth nominal width of 65 mm.

[0011] The sole FIGURE of the drawing depicts in schematic manner a longitudinal section through a water meter, whose housing 1 comprises an inflow region 2 and an outflow region 4, which are aligned with one another on a longitudinal housing axis 12. Between the inflow region 2 and the outflow region 4 is coaxially disposed a measuring insert 3. This is developed as a Woltmann meter, against which the flow is directed in the direction of arrow 5 and which comprises two eggcup-form holding means 6, 7. The holding means 6 is disposed upstream, thus is associated with the inflow region 2, while the holding means 7 is disposed downstream, and is thus located adjacent and opposite to the outflow region 4. The holding means 6, 7 are mounted with (not shown) stays on a measuring annulus 3.1 also belonging to the measuring insert 3. Between holding means 6 and 7 is disposed an impeller wheel 8, which comprises an impeller wheel hub 8.1 and vanes 8.2 disposed thereon and distributed over the circumference. These vanes 8.2 project beyond the circumference of the holding means 6 and 7 into an annular channel 16 formed between the wall of the holding means 6 and 7 and the measuring annulus 3.1. The impeller wheel 8 is rotatably supported via pins 17, 18 on holding means 6 or 7, respectively. The rotational movement of the impeller wheel 8 resulting from the stream incidence of the water flowing through the housing 1 is transmitted via a (not shown) shaft onto a meter also not shown, which is fastened above the measuring insert 3 on housing 1. The meter as well as also the transmission mechanism are within the scope of prior art, such that here more detailed or further explanations are unnecessary.

[0012] The drawing depicts a housing 1 which is provided for the connection to a pipe line with the nominal width of 50 mm. The inner contour of the inflow region 2 as well as the inner contour of the outflow region 4 are represented in solid lines for this meter. The inner contours of housing 1 for the connection to the pipe lines having the nominal widths of 80 and 100 mm are drawn in this drawing in dot-dash lines in order to make further graphic representations superfluous.

[0013] Common to the water meters of the nominal width-group is a first zone 10, adjacent to the holding means 6 of measuring insert 3, of the inner contour of the inflow region 2, which conically tapers in the direction toward an inflow origin 9 and opens into it approximately with diameter D of the annular channel 16.

[0014] For the smallest nominal width of 50 mm this first conical zone 10 continues as a second conical zone 11 up to the inflow origin 9.

[0015] In the case of the water meter for a mean nominal width of 80 mm, adjoining the zone 10 adjacent to the holding means 6 of the measuring insert 3 is a zone 13, extending up to the inflow origin 9 parallel to the longitudinal axis 12 of the meter, of the inner contour of inflow region 2. By parallel is also understood a nearly parallel extension which can be present for reasons, for example, of casting.

[0016] Apart from the three nominal widths of 50, 80 and 100 mm, in the nominal width-group can also occur a further mean nominal width of 65 mm. In this case, similar to the nominal width of 80 mm, an inner contour can result, which extends parallel or nearly parallel to the longitudinal axis 12 of the meter, adjoins zone 10 but is adjusted in accordance with the nominal width of 65 mm.

[0017] For the greatest nominal width of 100 mm the zone 13, extending parallel to the longitudinal axis 12 of the meter, transitions into a conically flaring zone 14 before the inflow origin 9.

[0018] This inner contour of the inflow region 2 developed in the case of the three or four water meters of the nominal width-group for the differing nominal widths signifies that, in the case of the smallest nominal width of 50 mm, the inner contour conically flaring from the inflow origin 9 decreases the velocity of flow up to the measuring insert 3, that in the case of the water meter with the mean nominal width of 80 mm or in the case of the water meter with the nominal width of 65 mm, the velocity of flow is only decreased in zone 10, and in the case of the water meter with nominal width 100 mm the velocity of flow in zone 14 is initially increased, subsequently is kept constant and in zone 10 is again decreased. Hereby, in cooperation with the holding means 6, uniform flow conditions, i.e. a substantially rectangular velocity distribution 19 with stream lines that are directed substantially parallel to the wall of the annular channel 16 can be attained directly in front of the impeller wheel 8.

[0019] The upstream holding means 6 forms a stream incidence body for the water flowing into the housing in the direction 5. The water stream is divided on holding means 6 and subsequently flows through the annular channel 16 in order to drive the impeller wheel 8. The holding means 6 comprises a perpendicular face of incidence 6.1, which transitions in a radius 6.2 into a slightly conically diverging shell surface. This development ensures that even with the smaller nominal widths, in particular with the smallest nominal width of 50 mm, the stream lines uniformly permeate the annular channel 16 directly in front of the impeller wheel 8 with substantially parallel direction to the wall of the annular channel 16.

[0020] In practice it is useful to develop the inner contour of the outflow region 4 such that it is identical to the inner contour of the inflow region 2.

[0021] The invention is not only applicable with the represented water meter but also with combination water meters, which are comprised of a main meter disposed in a main line for the acquisition of greater throughflows and a secondary meter disposed in a secondary line for the acquisition of smaller throughflows as well as a switch-over valve with a closure member effected counter to the flow 5, which, in the closed position, is in contact on a valve seat and enables or blocks the throughflow through the main meter upon reaching a specific limit throughflow. 

1. Water meter for the installation in pipe lines of a nominal width-group with successive nominal width, with a housing (1) with aligned inflow region (2) and outflow region (4) and a measuring insert (3) disposed coaxially between them, which is identical for all nominal widths of the nominal width-group and comprises a measuring annulus (3.1) in which are coaxially disposed an upstream holding means (6) and a downstream holding means (7), between which an impeller wheel (8) is rotatably supported, whose vanes (8.2) project into an annular channel (16) formed between the holding means (6, 7) and the measuring annulus (3.1), characterized in that the inner contour of the inflow region (2) and the outer contour of the upstream holding means (6) are developed such that, independently of the nominal width of the connected pipe line, in the annular channel (16) directly in front of the impeller wheel (8) a substantially rectangular velocity distribution obtains with stream lines directed substantially parallel to the wall of the annular channel (16).
 2. Water meter as claimed in claim 1, characterized in that the upstream holding means (6) comprises a substantially perpendicular face of stream incidence (6.1), which transitions into a cylindrical or slightly conically diverging shell surface (6.3), which forms the inner wall of the annular channel (16), with the transition being implemented such that directly in front of the impeller wheel (8) a substantially rectangular velocity distribution obtains.
 3. Water meter as claimed in claim 3, characterized in that the transition is a radius (6.2).
 4. Water meter as claimed in one of the preceding claims, characterized in that a zone (10), adjacent to the upstream holding means (6), of the inner contour of the inflow region (2) is identical for all nominal widths of the nominal width-group, in that it tapers in the direction toward the inflow origin (9) and opens toward the holding means (6) approximately with the diameter (D) of the annular channel (16).
 5. Water meter as claimed in claim 4, characterized in that the conical taper of zone (10) continues as a second tapering zone (11) for the smallest nominal width of the nominal width-group up to the inflow origin (9) and there ends with the smallest nominal width.
 6. Water meter as claimed in claim 4, characterized in that adjoining the zone (10) for one or several mean nominal widths is a zone (13) of the inner contour, extending up to the inflow (9) parallel or nearly parallel to the longitudinal axis (12) of the water meter, which ends there with the particular mean nominal width.
 7. Water meter as claimed in claim 4, characterized in that adjoining the zone (10) for the greatest nominal width is a zone, extending parallel or nearly parallel to the longitudinal axis (12) of the water meter, of the inner contour, which transitions into a zone (14) flaring conically before the inflow origin (9) to the greatest nominal width.
 8. Method for operating water meters for the installation in pipe lines of a nominal width-group with successive nominal widths, wherein the water meter comprises a housing (1) with aligned inflow region (2) and outflow region (4), between which is disposed coaxially a measuring insert (3), which is identical for all nominal widths of the nominal width-group and comprises a measuring annulus (3.1), in which are disposed coaxially an upstream holding means (6) and a downstream holding means (7), between which an impeller wheel (8) is rotatably supported, whose vanes (8.2) project into an annular flow channel (16) formed between the holding means (6, 7) and the measuring annulus (3.1), characterized in that the water meters are operated such that, independently of the nominal width of the connected pipe line, directly in front of the impeller wheel (8) a substantially rectangular velocity distribution (19) obtains with stream lines directed substantially parallel to the wall of the annular channel (16). 